Receptor-mediated shifts in cGMP and cAMP levels in neuroblastoma cells.

3':5'-cGMP levels of neuroblastoma N1E-115 cells increase as much as 200-fold upon activation of muscarinic acetylcholine receptors, resulting in intracellular cGMP concentrations greater than 600 pmol/mg of protein. The cells also have receptors for adenosine which mediate an increase in 3':5'-cAMP levels. Unexpectedly, prostaglandin E1 was found to increase the concentrations of both cGMP and cAMP. Carbamylcholine, adenosine, and PGE1 were added to cells separately and in pairs to determine the effect of one compound on cell responses to another. Reciprocal inhibition, unilateral inhibition, additive, and nonadditive responses were observed with respect to cGMP and cAMP levels when different pairs of receptors were activated simultaneously.